U.S. patent number 4,176,061 [Application Number 05/883,401] was granted by the patent office on 1979-11-27 for apparatus and method for treatment of fluid with ozone.
Invention is credited to Karel Stopka.
United States Patent |
4,176,061 |
Stopka |
November 27, 1979 |
Apparatus and method for treatment of fluid with ozone
Abstract
An apparatus and method for treatment of fluid such as water
with ozone. The apparatus comprises an ozonator for providing a gas
containing ozone and an aspirator which mixes the gas with water to
provide an ozone and water mixture having microbubbles of gas
therein. The mixture is then circulated through an elongated
treatment conduit having a length of between about 20 and about 40
feet and a diameter less than about 1 inch to allow the gaseous
ozone to dissolve in the water. Throughout the length of the
conduit the ozone oxidizes impurities in the water and provides
water having a relatively high purity. In the method of the present
invention a liquid such as water is mixed with ozone and the
mixture is then circulated through an elongated treatment conduit
to allow for dissolution of the ozone into the water and to provide
purified water. The ozonator used to provide ozone is capable of
providing a gas having at least about 1.2 weight percent ozone,
preferably a gas having an ozone concentration approaching 2 weight
percent. Gas having a high concentration of ozone is provided by a
novel ozonator comprising a plurality of electrodes connected in
series by gas flow lines.
Inventors: |
Stopka; Karel (San Francisco,
CA) |
Family
ID: |
25382504 |
Appl.
No.: |
05/883,401 |
Filed: |
March 6, 1978 |
Current U.S.
Class: |
210/760; 210/127;
210/192; 210/205 |
Current CPC
Class: |
C02F
1/78 (20130101) |
Current International
Class: |
C02F
1/78 (20060101); C02B 001/38 () |
Field of
Search: |
;210/63Z,127,134,177,192,205 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Wyse; Thomas G.
Attorney, Agent or Firm: Fishman and Van Kirk
Claims
What is claimed is:
1. An apparatus for purifying water comprising:
a first ozone generator, said first ozone generator including a
pair of spacially displaced electrodes and means for creating an
ionizing electrostatic field between said electrodes, said
electrodes defining a passage for the flow of gas through said
first ozone generator;
at least a second ozone generator, said second ozone generator
including a pair of spacially displaced electrodes and means for
creating an ionizing electrostatic field between said electrodes,
said electrodes of said second ozone generator defining a passage
for the flow of gas through said second ozone generator;
means connecting the gas flow passages of said first and second
ozone generators in a series, said connecting means comprising a
conduit;
means for delivering air to a first end of the gas flow passage of
said first ozone generator whereby a corona discharge will be
established in said first ozone generator and the air will be
partially ozonated, the ozone concentration in the air thereafter
being increased in said second ozone generator to a percent by
weight of the air exiting said second ozone generator exceeding
1.2%;
a fluid treatment conduit, said fluid treatment conduit being
partially in the form of a spiral and having a length of at least
10 feet, said fluid treatment conduit having an inner diameter of
less than 1 inch and being free of turbulence promoting
irregularities;
means for supplying water to be purified to a first end of said
fluid treatment conduit under a pressure of at least two
atmospheres;
means for producing and causing entrainment of microbubbles in the
water flowing through said fluid treatment conduit, said
microbubbles having an average diameter in the range of 10 to 20
microns and being uniformly dispersed in the water, said
entrainment causing means being located adjacent the first end of
said conduit;
means for delivering the ozonated air exiting the gas flow passage
of said second ozone generator as the supply gas to said
entrainment causing means whereby the microbubbles entrained in the
water include ozone molecules; and
storage tank means, said storage tank means being connected to the
discharge end of said fluid treatment conduit.
2. The apparatus of claim 1 further comprising:
activated carbon filter means for filtering water withdrawn from
said storage tank means.
3. The apparatus of claim 1 further comprising:
means for sensing the level of liquid in said storage tank
means;
means for deenergizing the field creating means of said first and
second ozone generators when the level of water in said storage
tank means exceeds a predetermined level; and
means for discontinuing the supply of water to said apparatus when
the level of water in said storage tank means exceeds the
predetermined level.
4. The apparatus of claim 1 further comprising:
means for cooling water withdrawn from said storage tank means.
5. The apparatus of claim 4 further comprising:
activated carbon filter means for filtering water withdrawn from
said storage tank means.
6. The apparatus of claim 5 further comprising:
heater means for heating water withdrawn from said storage tank
means.
7. A method for the purification of water comprising:
establishing a corona discharge in an air stream to partially
ionize the air and generate ozone molecules;
establishing a second corona discharge in the stream of partially
ionized air to increase the percent by weight of ozone in the air
stream to an amount exceeding 1.2%, the sequential subjection of
the air stream to the first and second corona discharges being
spaced in time;
dividing the ionized air stream into microbubbles having an average
diameter of from 10 to 20 microns;
entraining the microbubles in a stream of water to be purified;
maintaining a hydraulic pressure of at least two atmospheres in
said stream of water while causing the stream to travel along a
spiral path for a distance of at least ten feet while the ozone
molecules are dissolved therein; and
collecting the water stream in a storage container.
Description
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to purifying liquids. More particularly, the
invention relates to a method of and an apparatus for purifying
drinking water for domestic, office, plant, restaurant, hotel and
similar use.
(2) Description of the Prior Art
It is common practice to purify drinking water by addition of
chemicals to the water. The most common chemical treatment is by
the addition of chlorine to water. However, the use of chlorine has
long been questioned. For several decades Western European
scientists, such as Torricelli, have believed that continual
absorption by the human organism of small quantities of chloring
produce diseases such as hardening of the arteries and damage to
liver and kidneys. Torricelli, Alfred. Drinking Water Purification.
Adv. Chem. Ser. 21:453-465. (1959)
In 1928 Duggeli published a paper questioning the ability of
chlorine to function effectively as a bactericide. He concluded
that chlorine was a rather slow working bactericide and that either
a low temperature of the water or a high percentage of organic
matter in the water greatly slowed down the bactericidal action of
chlorine. He also reported that small doses of chlorine did not
kill bacteria but only paralyzed them thus making possible
subsequent return to normal bacterial growth rates. He also found
that, in order to obtain an absolutely lethal bactericidal effect
with chlorine, a rather high dosage of chlorination must be used.
It has also been found that the ability of chlorine to work as a
bactericide is highly sensitive to parameters in the water, that
is, the length of time the chlorine is in the water, the presence
of heavy metals, the pH and the temperature of the water. Thus, for
effective sterilization of water, precise and certain conditions
must be established in order to obtain the desired results. Travaux
de chimie alimentaire et d'hygiene 1926-1928 "Beitrag zur Frage der
Wirkung von Chlor auf die Bakterien des Wassers."
More recently, studies have shown that several of the chlorinated
hydrocarbons are carcenogenic. EPA Environmental News, EPA Releases
Results of National Drinking Water Survey. April 1975. R-89. The
United States Environmental Protection Agency's National Survey
conducted on potable water in 1975 indicated that chlorinated
hydrocarbons, several of them carcenogenic, existed above
permissible levels in seventy-nine cities. In only two cities
tested were the levels of chlorinated hydrocarbons below the
permissible level. Both of these cities used ozone to treat water.
Internal Ozone Institute. Press Release: Ozonation produces highest
quality U.S. Drinking Water. Apr. 28, 1975.
The ability of ozone to purify drinking water has been appreciated
for some time. According to Bringmann, the rate of destruction of
bacteria by ozone is 1 to 2 orders of magnitude faster than that of
chlorine. (1) Bringmann, G. 1954. Determination of the lethal
activity of chlorine and ozone on E. Coli, Z. Hyg. Infektionskr.
139: 130-139. (2) Bringmann, G. 1954, Die Wirkung von Ozon auf
Organismen des Trinkwassers, (The action of ozone on organisms in
water) A. Hyg. Infektionskr. 139: 333-337. Fetner and Ingols have
reported that the bacterial action of chlorine is progressive while
the bacterial action of ozone is sudden after reaching threshold
value. Fetner, R. H., and R. S. Ingols. 1956. A Comparison of the
Bactericidal Activity of Ozone and Chlorine Against Escherichia
Coli at 1.degree.; J. Gen. Microbiol, 15(2): 380-385. Kessel et al
have shown that polio virus treated with chlorine to a residual
value of 0.5 mg per liter to 1 mg per liter will be rendered inert
in 11/2-3 hours while treatment with ozone to a residual value of
0.045 to 0.45 mg per liter will render polio viruses inert in only
two minutes. Kessel, J. F., D. K. Allison, F. J. Moore, and M.
Kaime. Comparison of Chlorine and Ozone as Virucidal Agents of
Poliomyelitis Virus. Proc. Soc. Exp. Biol. Med. 53(1): 71-73.
1943.
There are many publications that disclose the benefits of treating
water with ozone. To summarize, these publications disclose that
ozone treatment systems in general are capable of removing the
following undesirable substances from water: organics, heavy metals
such as manganese, pathogens such as virus, spors, fungii,
mercaptans and E. coli bacteria, formaldehyde, pesticides,
detergent and chlorine and halogenated hydrocarbons.
The conventional method of dissolving ozone in water is to bubble
the gaseous ozone upwardly through the water. U.S. Pat. No.
3,699,776 discloses an ozone purifier for a pressurized water
cooler wherein gaseous ozone is introduced through a diffuser into
a tank containing water. The ozone is allowed to bubble through the
water.
U.S. Pat. No. 3,726,404 discloses an apparatus for purifying water
wherein a batch of water is contained in a tank and fine bubbles of
ozone are allowed to rise through the water. Once the batch of
water is treated with a sufficient amount of ozone, the batch is
transferred to a storage tank.
U.S. Pat. No. 3,421,999 discloses an ozone generator for purifying
contaminated fluid wherein ozone is injected through an aspirator
into a stream of contaminated fluid. The mixture of ozone and fluid
is then immediately discharged into a pipeline which directs the
fluid to storage.
U.S. Pat. No. 3,692,180 discloses a water purifier wherein ozone is
fed to the bottom of a container. A diffuser breaks the ozone into
small bubbles that rise through the water in the container.
U.S. Pat. No. 2,970,821 discloses a water treatment system wherein
ozone is introduced directly into a water line through an injector.
Immediately after the injection of ozone the water is added to a
mixing vessel wherein the ozone and water are mixed and the water
treated.
The above-mentioned patents disclose systems wherein ozone is
bubbled through water. Although a portion of the ozone is dissolved
in the water, the dissolution rate of ozone into the water is very
low because of the generally low partial pressure of ozone in the
water. Thus, the treatment time is extended, and, when the ozone
bubbles reach the surface of the water, the bubbles burst and a
large amount of undissolved ozone is wasted.
One object of the invention is to provide a water treatment system
wherein purified water may be continuously produced.
Another object of the invention is to provide a system which
provides for large amounts of ozone to be dissolved into water.
Another object of the invention is to contact the water with ozone
bubbles for relatively long periods of time to provide for
dissolution of the ozone into the water.
SUMMARY OF THE INVENTION
The invention provides an apparatus and a method for purifying
liquids such as water. The apparatus comprises an ozone generator
which produces ozone from oxygen in the air which is fed into the
ozone generator. The gas containing ozone is mixed with the liquid
to be purified in an aspirator which provides for a liquid and
ozone mixture. The mixture is then circulated through an elongated
treatment conduit of sufficient length to allow for the ozone and
liquid to remain in contact for a sufficient amount of time to
dissolve ozone in the liquid and purify the liquid. The length and
diameter of the elongated treatment conduit will be chosen so that
the ozone and the liquid in the mixture remain in contact for a
sufficient amount of time to dissolve ozone in the liquid and
purify the liquid. In the preferred embodiment the elongated
treatment conduit is at least about 10 feet long, most preferably
between about 20 and about 50 feet. It is preferred that the inner
diameter of the elongated treatment conduit be less than about 1
inch, most preferably about 1/2 inch. It is preferred that the
liquid and ozone mixture be circulated through the elongated
treatment conduit under a pressure in excess of atmospheric
pressure, preferably in excess of two atmospheres. The ozone
generator of the present invention uses air as a feed gas and
provides a gas having an unusually high ozone concentration, that
is an ozone concentration of at least about 1.2 weight percent,
and, preferably approaching two weight percent ozone. The ozone
generator comprises a plurality of electrodes connected in series
by air flow lines, wherein the first electrode tends to excite the
oxygen in the air and produce ozone. The ozonated air from the
first electrode is transported to a second electrode wherein the
second electrode produces a gas having an unexpectedly high
concentration of ozone. The ozone generator which comprises a
plurality of electrodes connected in series allows for the
production of a relatively high flow rate of ozone.
Thus, if desired, the fluid can be circulated continuously through
the elongated treatment conduit to produce a purified fluid. This
is a particularly important feature wherein the fluid to be
purified is water in that prior known treatment apparatus which
treat water with ozone work on the batch principle.
With the mixture of ozone and fluid being circulated under pressure
through the elongated treatment conduit, relatively high amounts of
ozone are dissolved into the fluid. This is particularly the case
because in a preferred embodiment of the invention, the novel
ozonator produces a gas having a relatively high concentration of
ozone.
It should be understood that the length and diameter of the fluid
conduit will be chosen based on factors including the types of
impurities which are to be removed from the liquid and the
concentrations of the impurities in the liquid. Thus, in the method
of purifying the liquid, it is initially necessary to chose an
elongated treatment conduit having sufficient length and diameter
to allow the ozone to contact the liquid for a sufficient amount of
time to allow the ozone to dissolve into the liquid and to purify
the liquid.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of the water treatment system;
FIG. 2 is an expanded view of the first portion of the elongated
treatment conduit shown in FIG. 1;
FIG. 3 is an expanded view of the intermediate portion of the
elongated treatment conduit shown in FIG. 1;
FIG. 4 is an expanded view of the final portion of the elongated
treatment conduit shown in FIG. 1;
FIG. 5 is a perspective view of the ozonator including a step-up
transformer with a high voltage secondary and ozone producing
electrodes;
FIG. 6 is the perspective view of a single ozone producing
electrode;
FIG. 7 is a plan sectional view along line 7--7 of FIG. 6 of the
ozone producing electrode.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, which is a schematic diagram of a preferred
embodiment of the present invention, the water treatment apparatus
is shown generally at 10 and includes container 11 for the water
which has been treated. Container 11 preferably has a cylindrical
shape, comprises transparent glass or plastic and is positioned
above cabinet 12 which contains the essential water treatment
parts. Untreated water is delivered to water treatment apparatus 10
through conduit 13. The inflow of water through conduit 13 is
controlled by solenoid valve 14. A second solenoid valve is
built-in ozonator 15 to protect ozonator 15 from seepage of water
into the ozone electrodes when the apparatus is not functioning.
Ozone gas is provided by ozonator 15 which is preferably an
ozonator of the type which will be described in detail hereinafter
in the discussion of FIGS. 5, 6 and 7. Ozone conduit 16 allows for
passage of the ozone gas provided by the ozonator to an aspirator
17 which mixes the ozone gas with the untreated water. The
aspirator 17 separates the ozone gas flow into tiny microbubbles
and mixes these microbubbles with the untreated water. The water
which is circulated through conduit 13 to aspirator 17 is under a
pressure in excess of atmospheric pressure and forces the ozone gas
and water mixture through elongated treatment conduit 18 which is
preferably coiled to provide a compact water treatment system.
During circulating through elongated treatment conduit 18 the water
is treated and is then delivered through elongated treatment
conduit 18 to water storage container 11.
The elongated treatment conduit 18 is a particularly important
aspect of the present invention. The function of elongated
treatment conduit 18 will be described with respect to FIGS. 2, 3
and 4 which show an expanded section of the elongated treatconduit
18 including the flow of the gaseous ozone and water mixture
therethrough.
It should be understood that ozone is a gas that is soluble in
water. Referring to FIG. 2, when the gaseous ozone and water
mixture is discharged from aspirator 17 and first enters elongated
treatment conduit 18, little or no gaseous ozone has dissolved in
the water, but rather there is a distinct phase difference between
the gaseous ozone and the water. The ability of ozone to purify
water is a function of the amount of ozone dissolved in the water
rather than the amount of gaseous ozone present as discrete bubbles
in the water. Since the amount of ozone that dissolves in a defined
amount of water at a given temperature is very nearly proportional
to the partial pressure of the ozone, it is desirable to circulate
the water through the elongated treatment conduit 18 under a
pressure which is in excess of atmospheric pressure. It is
preferred that the water treatment apparatus be designed to purify
not only water of average purity but also very impure water. Thus,
in the design of water treatment apparatus 10 there are important
parameters which must be met. Such parameters include the length,
l, of elongated treatment conduit 18, the inner diameter, d, of
elongated treatment conduit 18, the pressure of the ozone gas and
water mixture introduced into elongated treatment conduit 18, the
volume flow rate of the ozone and water mixture circulated through
elongated treatment conduit 18, the weight percent of ozone in the
gaseous ozone and water mixture, the weight percent of ozone in the
gas mixed with the water, the size of the microbubbles of gas
containing ozone, and the temperature of the water and ozone
mixture.
FIGS. 2, 3 and 4 illustrate the method by which the untreated water
is purified by the water treatment apparatus of the present
invention. FIG. 2 shows the aspirator 17 and the portion of
elongated treatment conduit 18 immediately downstream of the
aspirator 17. Although it should be understood that the flow
through elongated treatment conduit is continuous, FIG. 2 shows a
discrete portion 19 of the water and gaseous mixture. The length,
l, of elongated treatment conduit 18 is measured from the aspirator
to the end of elongated treatment conduit 18. Although it is
preferred that elongated treatment conduit have a constant
diameter, treatment conduits which have diameters which vary along
the length of the conduit may be used, so long as the mean diameter
is relatively small. As shown in FIG. 2, the gaseous ozone and air
mixture is ejected from aspirator 17 into elongated treatment
conduit 18 at time t.sub.o. At time t.sub.o, substantially all of
the ozone is in the gaseous form and very little of the ozone has
been dissolved into the water. The gaseous ozone is soluble in
water and dissolves in the discrete amount of liquid at a rate
proportional to the pressure of the gaseous ozone and water
mixture. Referring to FIG. 3, as the discrete portion 19 flows
through the elongated treatment conduit under pressure, the soluble
ozone gas dissolves into discrete portion 19 and the dissolved
ozone begins to oxidize impurities in the water. As the water
proceeds through elongated treatment conduit 18, discrete portion
19 at intermediate time t.sub.i, that is, a time at which discrete
portion 19 is somewhere between aspirator 17 and container 11,
ozone is continually being dissolved into the water. It should be
understood that during movement of discrete portion 19 through
elongated treatment conduit 18, an equilibrium between the gaseous
ozone and the dissolved ozone is not reached because as the ozone
is dissolved into the water it is consumed in the oxidation process
in which impurities are oxidized and oxygen is liberated.
As shown in FIG. 4, as discrete portion 19 of water reaches the end
of elongated treatment conduit 18, a substantial portion of the
ozone has been consumed during the movement of the discrete portion
through elongated treatment conduit 18. At the final stages of the
treatment process, at time t.sub.f, treatment of the water is
finished and purified water having relatively high amounts of
dissolved and gaseous oxygen is provided. Although some
purification may occur in container 11, a large portion of the
purification occurs in elongated treatment conduit 18 because the
liquid in the conduit is under pressure. When the liquid in the
conduit is released into container 11, the pressure of the water
approaches atmospheric pressure and the dissolution of any
remaining ozone gas into the water occurs at a low rate.
In order to obtain desired dissolution rates of ozone into the
water, it is desirable that the pressure of the mixture within the
elongated treatment conduit be substantially above atmospheric
pressure. It is particularly preferred that the pressure within the
conduit be in excess of two atmospheres. The upper limitation on
the pressure of the mixture within elongated treatment conduit 18
is the maximum pressure the conduit can withstand. In general, the
pressure within elongated treatment conduit 18 is limited by the
pressure of the source of water, and it has been found that many
domestic sources provide water having water pressures in excess of
the proscribed minimum.
In order to insure intimate contact of the gaseous ozone
microbubbles with the water, it is preferable to provide an
elongated treatment conduit having a relatively small inner
diameter, that is, an inner diameter less than about 1 inch. The
lower limit on the inner diameter of the fluid conduit is limited
by the desired volume flow rate. A particularly preferred inner
diameter for the fluid conduit 18 is about 1/2 inch.
Another important parameter of the process is the length of
elongated treatment conduit 18. While the length will depend upon
the other parameters of the system, the length depends most heavily
on the degree of impurity of the water. In order to achieve
sufficient dissolution of the ozone in the water, it is preferable
to provide an elongated treatment conduit of a length of at least
10 feet. In areas where there are particularly high amounts of
impurities in the water, such as in cities, the length of the
elongated treatment conduit can be anywhere from about 20 to about
50 feet and most preferably from about 25 to about 40 feet.
However, it should be understood that there is really no upper
limitation on the length of elongated treatment conduit 18,
although, at lengths above about 50 feet little additional
purification is achieved.
Another important parameter of the present invention is the volume
flow rate. Although the volume flow rate is a function of some of
the previously mentioned parameters such as water pressure and
treatment conduit length and diameter, the flow rate is also a
function of viscosity and liquid to wall friction. It is generally
preferred that the volume flow rate be within the range of about 2
to about 5 gallons per minute.
It should be understood that the ozonator of the present invention
converts oxygen in air to ozone so that the gas provided at
aspirator 17 is a mixture of ozone plus other gases. It is
preferred that the weight percent of ozone in the gas introduced
into the aspirator be as high as possible. A preferred weight
percent range for ozone in a gas is at least about 1.2% to 2%.
It is desirable to minimize the size of the gaseous microbubbles
mixed with the water at the aspirator so as to provide maximum
surface area for dissolution of the gaseous ozone into the water.
It is particularly preferred that the average diameter of the
microbubbles be within the range of about 10 microns to about 20
microns.
Referring back to FIG. 1, treated water is delivered from elongated
treatment conduit 18 into container 11 and is available for any
use. Water treatment apparatus 10 may be provided with an activated
carbon filter 20 to remove impurities including particulate matter
from the ozone treated water. Although it is preferred that
activated carbon filter 20 be located downstream of the container
11, it should be understood that the activated carbon filter can be
placed immediately downstream of elongated treatment conduit 18 to
filter the water prior to storage in container 11. Optionally,
water treatment apparatus 10 may also include conventional water
heating and/or cooling devices, respectively indicated at 21 and
22, which provide heated or cooled water.
Water treatment apparatus 10 is provided with a control system
which allows for replenishment of treated water in container 11 as
the treated water is consumed. Container 11 is provided with a
water level sensor 23 which senses the level of the water in
container 11 and signals the control system to allow opening of
valve 14 and ignition of ozonator 15 to provide flow of ozone when
a predetermined low level is reached. When container 11 is filled
to a predetermined level, the control system closes valve 14 and
terminates the production of ozone.
In treating waters contaminated by organics, bacteria, virus, heavy
metals such as iron or manganese or traces of industrial
contaminates such as phenols, formaldehyde, pesticides and other
chemical complexes, for maximum treatment by ozone, a high
concentration of ozone in the ozonized air is essential. Existing
ozone generators under operating conditions deliver a maximum of
about 1 weight percent ozone concentration when air is used as the
feed gas. When pure oxygen is used as the feed gas, existing
ozonators provide a gas having about 2 weight percent ozone.
However, to supply pure oxygen for domestic use or for other uses
to which the invention of this application can be used, is not very
practical, and, if oxygen is used, the apparatus and process would
be very costly.
With gases having 1 weight percent ozone concentration, only
partial purification of the water takes place. However, it has been
found that a gas having at least a 1.2 weight percent ozone
concentration and preferably about a 2 weight percent ozone
concentration provides for excellent purification. To provide a gas
having 2 weight percent ozone, a novel type of ozone generator is
used.
Contrary to known ozone generators where ozone is produced in a
single set of electrodes, in the present invention ozone is
produced in two or more electrodes aligned in series. FIG. 5 shows
an expanded schematic view of an ozonator which may be used in the
present invention. Ozonator shown generally at 15 comprises stepup
transformer 24 having a high voltage secondary and electrodes 25,
26 and optionally 27 which are connected in series by air flow
passages 28, 29 and 30. As a result of the above-described
structure, the first electrode can produce 100 milligrams of ozone
per hour. The air and ozone mixture which leaves electrode 25
through flow line 29 is then subjected to a second processing in
second electrode 26. When the ozone leaves the second electrode 26,
the production of ozone will exceed 200 milligrams per hour, and
will approach approximately 40% more than the expected output, or
280 milligrams per hour. Optionally, when the third electrode 27 is
used, the ozone production will not be 300 milligrams per hour, but
rather, as much as approximately 70% more, or 510 milligrams of
ozone per hour. The gas produced through line 16 has an ozone
concentration in excess of about 1.2 weight percent and generally
has an ozone concentration of about 2 weight percent. Ozone in a
concentration of 2 weight percent is 2 to 3 times more powerful for
oxidation and purification purposes than a gas having a 1 weight
percent concentration. Whether two, three or even more electrodes
are hooked in series will depend upon the size of the ozone
generator to be used and the desired flow rates and concentrations
of the ozone. In the case of domestic ozone equipment, three
electrodes may be used. In a large industrial ozone generator
operating at a 9,000 volt secondary voltage and 100 Hz frequency,
the intensity and heat inside the corona discharge chamber may be
such that the ozone produced in the first two electrodes may be
decomposed in the third electrode. In this instance only two
electrodes will be used.
As shown in FIG. 5, solenoid valve 31 prevents water from seeping
back into the electrodes.
Referring to FIGS. 6 and 7, these FIGURES show an expanded view of
a single electrode, for example, electrode 25. Electrode 25
includes an outside cylindrical casing 32 made of for example high
purity aluminum, such as, for example, aluminum having technical
number 1100H14. Extending into the interior of casing 32 are flow
lines 28 and 29. Spaced inwardly from casing 32 is a cylindrically
shaped glass or ceramic dielectric material 33 to provide an
airflow and corona discharge gap 34. High voltage line V is
connected to the aluminum casing 33 and the ground line is
connected to the dielectric material 33. Cover 35 closes the top of
air passage 34 and supports casing 32 and dielectric material
33.
During the operation of ozonator 15, air is delivered through flow
line 28 to electrode 25 where the oxygen molecules in the air are
excited and a small amount of ozone is produced. This ozonated air
is delivered through flow line 29 to electrode 26 wherein the gas
is subjected to further corona discharges and additional ozone is
produced. The ozonated air can then be either led to electrode 27
through flow line 30 or can be used in the purification of water
after the air has been subjected to two electrodes.
Although it is preferred to use cylindrical electrodes in the
production of ozone, it should be understood that any configuration
of electrodes can be used such as, for example, plate
electrodes.
It should be understood that the voltage in an ozonator for use in
domestic water apparatus is provided by a step up transformer with
a high secondary voltage. In larger units, the power is modulated
by means of solid state circuitry, high voltage transformers, DC
inverters and electrodes made out of ceramic or other high strength
dielectric material. In each instance, as should be understood by
one skilled in the art, the modulated electrical power is designed
to suit the requirements of the particular ozone producing
electrode.
While preferred embodiments have been shown and described, various
modifications and substitutions may be made thereto without
departing from the spirit and scope of the invention. Accordingly,
it is to be understood that the present invention has been
described by way of illustration and not limitation.
* * * * *